Occurrence of PBDEs in surface sediments of metropolitan rivers: Sources, distribution pattern, and risk assessment

Sources, concentrations, and ecological risk of polybrominated diphenyl ethers (PBDEs) were investigated in surface sediments from 33 stations in Danshui River basin (Taiwan) in 2015. High spatial variation in total PBDEs (Σ₁₉PBDEs) in sediments was found ranging from 2.3 to 10,490 ng g^-1 dw. The effects of the physicochemical characteristics, total organic carbons (TOC) and grain size of sediments on the levels and distributions of PBDEs were investigated. Significant linear correlations were observed for PBDE concentrations with TOC (r² = 0.45, p < 0.01) and fine sediment fraction (grain size <1 mm; r² = 0.2, p < 0.05). Spatial distributions of Σ₁₉PBDEs showed that sediment samples were likely impacted by point source inputs. BDE209 was the dominant congener, accounting for 77.5%-99.9% of the Σ₁₉PBDEs in sediments suggested that commercial deca-BDE mixtures are the major sources of PBDEs in Danshui River basin. Regarding ecological risk estimation, high molecular PBDEs pose a high risk quotient (RQ > 1) to sediment dwelling organism along the 33 sampling stations, suggesting that penta-BDEs and deca-BDE are the major ecological risk drivers in the Danshui River basin.